From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with SMTP id 2CDA16B004A for ; Wed, 6 Oct 2010 23:23:40 -0400 (EDT) Received: from m1.gw.fujitsu.co.jp ([10.0.50.71]) by fgwmail7.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o973Nbgc019263 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Thu, 7 Oct 2010 12:23:37 +0900 Received: from smail (m1 [127.0.0.1]) by outgoing.m1.gw.fujitsu.co.jp (Postfix) with ESMTP id 1458445DE56 for ; Thu, 7 Oct 2010 12:23:35 +0900 (JST) Received: from s1.gw.fujitsu.co.jp (s1.gw.fujitsu.co.jp [10.0.50.91]) by m1.gw.fujitsu.co.jp (Postfix) with ESMTP id 854A045DE51 for ; Thu, 7 Oct 2010 12:23:34 +0900 (JST) Received: from s1.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s1.gw.fujitsu.co.jp (Postfix) with ESMTP id 4DEE41DB805A for ; Thu, 7 Oct 2010 12:23:34 +0900 (JST) Received: from m106.s.css.fujitsu.com (m106.s.css.fujitsu.com [10.249.87.106]) by s1.gw.fujitsu.co.jp (Postfix) with ESMTP id B2AA31DB804E for ; Thu, 7 Oct 2010 12:23:33 +0900 (JST) Date: Thu, 7 Oct 2010 12:18:16 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [RFC] Restrict size of page_cgroup->flags Message-Id: <20101007121816.bbd009c1.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20101007031203.GK4195@balbir.in.ibm.com> References: <20101006142314.GG4195@balbir.in.ibm.com> <20101007085858.0e07de59.kamezawa.hiroyu@jp.fujitsu.com> <20101007031203.GK4195@balbir.in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: balbir@linux.vnet.ibm.com Cc: containers@lists.linux-foundation.org, "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" List-ID: On Thu, 7 Oct 2010 08:42:04 +0530 Balbir Singh wrote: > * KAMEZAWA Hiroyuki [2010-10-07 08:58:58]: > > > On Wed, 6 Oct 2010 19:53:14 +0530 > > Balbir Singh wrote: > > > > > I propose restricting page_cgroup.flags to 16 bits. The patch for the > > > same is below. Comments? > > > > > > > > > Restrict the bits usage in page_cgroup.flags > > > > > > From: Balbir Singh > > > > > > Restricting the flags helps control growth of the flags unbound. > > > Restriciting it to 16 bits gives us the possibility of merging > > > cgroup id with flags (atomicity permitting) and saving a whole > > > long word in page_cgroup > > > > > > Signed-off-by: Balbir Singh > > > > Doesn't make sense until you show the usage of existing bits. > > ?? > Limiting something for NOT EXISTING PATCH doesn't make sense, in general. > > And I guess 16bit may be too large on 32bit systems. > > too large on 32 bit systems? My intention is to keep the flags to 16 > bits and then use cgroup id for the rest and see if we can remove > mem_cgroup pointer > You can't use flags field to store mem_cgroup_id while we use lock bit on it. We have to store something more stable...as pfn or node-id or zone-id. It's very racy. Thanks, -Kame -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org